Optical gun sight with horizontal and vertical deflection adjustments



1 8 3; 8 5 v 2 J- lll w w. M. CADY OPTICAL GUN SIGHT \WITH HORIZONTAL AND VERTICAL DEFLECTION ADJUSTMENTS Filed July 9, 1945 2 ShetS-Sheet 1 2 1 L 1 m a J INVENTOR WILLOUGHBY M. CADY ATTORNEY FIG.2

Jan. 11, 1949. w M. CADY- OPTICAL GUN SII-IT WITH HORIZONTAL AND VERTICAL DEELECTION ADJUSTMENTS Filed July 9, 1945 2 Sheets$heet 2 INVENTOR WILLOUGHBY M. -CADY ATTORNEY y H 2,458,831 7 ()PTICAL GUN SIGHT HORIZONTAL AND VERTICAL' DEFLECTION ADJUST- Willoughby Cady, Cambridge, Mass assignor, by mesne assignments, ,to the United States of America as representetlby the Secretary of War It is an object of the This invention relates to precision aiming apparatus and more particularly to apparatus for improving the accuracy of optical sights on weap- Optical sights have been developed for use on guns or rocket launchers that employ a movable reflector that is adjustable for the purpose of setting the correct elevation on the gun 01' rocket launcher. In many of these sights'no provision is made for correctionsat right angles to the path of the projectile to compensate for wind; motion of the target and so forth. Such a correction is necessary where accurate fire must be directed at atarget. a; i present invention, there- "fore, to improve existing reflector sights so that a correction may be made parallel to the pivotal axis of the reflector. l

A further object of the invention is to provide simple, novel sight .means which allow the introduction of corrections in both azimuth and elevation. j

In accordance with the present invention there are provided means for viewing a target, means for superimposing a suitable reference image on the image of the target and means-for adjusting the position of the reference image with respect to the target image.

For a better understanding of'the invention together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings in which:

Fig. l is a schematic view showing the essential elements of a reflector sight embodying the present invention;

'Fig. 2 is a sectional --perspecti ve view of the angular deflection unit of Fig. 1; f L, V I- Fig. 3 is a schematic perspective'view showing the efiect of a glass wedge on abeam of light;

Fig. 4 is a schematic perspective view showing the effect of two coaxially placed glass wedges on abeam oflight;

Fig. 5 is a diagrammatic perspective view illustrating how two units embodying the present invention may be employed to provide two corrections at right angles in a reflector type sight; and

Fig. 6 shows how two units of the invention may be employed to provide two corrections at right angles with a telescopic sight.

Referring now more particularly to Fig. 1, there is shown an optical sight comprising a reflector ID, a lens l2, a screen l4 and a source of illumination 16. The position of obserders eye wAvDlicat-iondulyil,.1945, :Serial No. 604 05l 1 cl im.

(dismal osition "6f the target is a is. at l8 and the :p

peintZll. f gj iIn the operation of this type of sight a set bf cross-hairs or other aiming device is marked t onscreen M. The light from source It causes an image of these cross-hairs to be thrown upon reflector .-l0.--,Refiector I is a piece of unsilvered glass with polished .faces. ,-Partial reflection oc. curs 'at the surface of ireflectolflrlil so that at 1Q; point [8 the observer seestarget 20 with a set of cross-hairs superimposed upon it. When the center of the cross-hairs coincides with the selected target the sight is properly oriented. In many reflector sights reflector lllis pivoted about an axis 22. When reflector l0 moves in the directions shown by thearrows inFig. '1, ;the appar ent position of the cross-hairs on the target moves along a vertical line passing through the target. It can be seen that this adjustment 20 could be used to make adjustments in elevation of the gun associated with this sight. These adjustments in elevation change the position at which the projectiles will fall alon the line of flight of the projectiles. The angular deflection unit 24, Fig. 1, permits shifting the apparent position of the cross-hairs in a direction at right angles to theshift caused by adjustment of rehave no lateral or axial movement relative tpmne another. An idler gear 36 is supported by? suitable projection on ring 34 and meshes with cirin cular racks on rings and .32., Ring 38 is prov ided with a knurled grip SB. A circular scale marked on the outer cylindrical surface 40 of ring 30 and a pointer iZsecured to ring 34 provide means for indicating the position of ring 36. The upper face of wedge 28 and the lower face of wedge 28 are maintained in planes perpendicular to the axis of ring 34. This may be done by suitable design of rings 30 and 32 or tapered crescents may be employed (as illustrated by crescents M and 45) to support the narrow portions of the glass wedges. The operation of the deflection unit shown in Fig. 2 may be best understood by reference to Figs. 2, 3 and 4.

Wedge 26 shown in Fig. 3 is a cylindrical prism having a base 48 perpendicular to the axis 49 of the prism and a second base 5!] at a slight angle to axis 49. If a beam of light parallel to the axis 49 strikes base 48 it will pass through wedge 28 emerging from base 50 at an angle with axis 49. The size of this angle is determined by the angle that base 50 makes with axis 49 and the material of which wedge 26 is made. If wedge 25 is now rotated about axis 49 the beam of light emerging from base 59 will describe a conical path in space as shown in Fig. 3.

Fig, 4 shows two identical wedges 26 and 28 intercepting a beam of light. The inclined base 52 of wedge 29 is placed uppermost. of wedge 26 is aligned with axis 54 of wedge 28 and wedges 26 and 28 are so oriented that base 50 is parallel to base 52 it can be shown that a Q If axis 49 beam of light parallel to axis 49 striking base 48 direction, the position at which said image will will emerge from base 55 parallel to axis 54. It can also be shown that if wedge 29 is rotated in one direction, say clockwise, while wedge 28 is rotated an equal amount in the opposite direction the beam of light emerging from base 55 will move back and forth in a plane perpendicular to base 56, as shown in Fig. 1. Theangle that the beam of light makes with axis 54 depends upon the material from which the wedges are made, the angle the inclined base makes with the axis of each wedge and the angle of rotation of the wedges from their initial position. Y

that wedge 26 may be rotated manually by means of grip 38 while wedge 28 is moved in an. equal inay be indicated by means of scale 40 and reference pointer 42. Scale 40 may be calibrated in any convenient manner as, for example, in degrees of displacement of the line of sight to the right or left of normal.

Referring now to Fig. 1, it can be seen that unit 2 may be so mounted that the apparent displacement of the cross-hairs caused by unit 24 is at right angles to the apparent displacement caused by reflector l0.

Referring now to Fig. 5 there is shown a reflector sight employing two angular correction units 69 and 62, a cross-hair unit 66 and a reflector 66. Units 69 and 62 are so oriented that the deflections of the beams caused by the two units are at right angles to each other. In this type of sight, reflector 96 may be fixed in. position since all necessary displacements of the light beam may be obtained from units 69 and 62. In the sight shown in Fig. 5 the line of sight is represented by line 68. If two angular correction units 10 and T2 are mounted coaxially with a telescopic sight, as indicated in Fig. 6, deflections of the line of sight in two directions may be obtained.

One of the chief advantages of this invention is that it may be adapted for attachment to existing sights. A second advantage is that by Referring once more to Fig. 2 it can be seen' 4 suitable selection of angles for the wedges and by careful construction of the supporting structure very accurate adjustments of the line of sight may be made.

3 fWhiIe there has been described what is at 'present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention.

What is claimed is:

In an optical gun sight for viewing a target, a reference reticle, a pivotable ray dividing means, means for projecting an image of said reticle upon said ray dividing means, a ray deflecting means optically interposed between said reference reticle and said ray dividing means, said ray deflecting means being adapted to change, in a horizontal strike said ray dividing means, said ray deflecting means including a pair of spaced coaxially disposed cylindrical optical prisms, said prisms having their bases, which are adjacent each other, disposed obliquely to their mutual axis and having their remaining bases disposed normally to their mutual axis, a circular rack secured to each of said prisms, said racks being coaxial with said prisms and of like diameter and facing each other, an idler gear in"mesh' with both of said racks and having the position of its axis of rotation fixed, means to revolve one of said prisms about its axis, means for pivoting the ray dividing means for changing, in'a vertical direction, the

. position at which the image will strike said ray REFERENCES CITED ,The following references are of record in the file of this patent: I

V UNITED STATES PATENTS Number Name" 1 Date 942,393 Konig "Dec. '7, 1909 1,088,701 I Humbrecht Mar. 3,1914 1,093,639 MacD0ugal1 2,394,521 Lynn Feb. 5, 1946 1 FOREIGN PATENTS Country i Date Great Britain g 1912 Great Britain -Q. May 17, 1935 ,N.umber Apr. 21,1914 

